Abrasive peeling apparatus

ABSTRACT

An abrasive peeling apparatus having a plurality of rotatable elongated rollers each with an abrasive outer surface including a helical configuration adapted to move the material to be peeled along the length of the rotatable rollers. Material to be peeled is fed into an inlet opening in one end of the apparatus, and the abrasive rollers are mounted to carry the product and to urge it toward the outlet end of the apparatus while peeling the same. A tumbling action is obtained partly by virtue of the fact that some of the abrasive rollers are spiraled in an opposite direction to others of the abrasive rollers, and partly due to the positioning of the rollers to form a generally arcuate lower surface of the apparatus. Driving means rotate each of the rollers, preferably in the same direction, and an adjustable discharge gate is provided to control the depth of the load and consequently the peeling force on the abrasive surfaces. Quickrelease mounting means are included for mounting the end of the rollers opposite the driving end. Each of the rotatable abrading rollers are mounted on a central shaft therethrough, and include an opening conforming to the size and shape of the central shaft. The abrading roller may include a plurality of smaller members in abutting end-to-end relationship to form a continuous abrading surface throughout the length of the roller.

United States Patent [1 1 Wallace July 17, 1973 [54] ABRASIVE PEELING APPARATUS [75] Inventor: Joseph E. Wallace, Creston, Iowa [73] Assignee: Vanmark Corporation, Creston,

Iowa

[22] Filed: Oct. 27, 1971 [21] Appl. No.: 193,134

Primary Examiner-Willie G. Abercrombie AttorneyHenderson & Strom 57 ABSTRACT An abrasive peeling apparatus having a plurality of rotatable elongated rollers each with an abrasive outer surface including a helical configuration adapted to move the material to be peeled along the length of the rotatable rollers. Material to be peeled is fed into an inlet opening in one end of the apparatus, and the abrasive rollers are mounted to carry the product and to urge it toward the outlet end of the apparatus while peeling the same. A tumbling action is obtained partly by virtue of the fact that some of the abrasive rollers are spiraled in an opposite direction to others of the abrasive rollers, and partly due to the positioning of the rollers to form a generally arcuate lower surface of the apparatus. Driving means rotate each of the rollers, preferably in the same direction, and an adjustable dis charge gate is provided to control the depth of the load and consequently the peeling force on the abrasive surfaces. Quick-release mounting means are included for mounting the end of the rollers opposite the driving end.

Each of the rotatable abrading rollers are mounted on a central shaft therethrough, and include an opening conforming to the size and shape of the central shaft. The abrading roller may include a plurality of smaller members in abutting end-to-end relationship to form a continuous abrading surface throughout the length of the roller.

14 Claims, 11 Drawing Figures PAIENIEBMWW. 3.145.914

sum 1 or '3 ABRASIVE PEELING APPARATUS BACKGROUND OF THE INVENTION Modern commercial food processing requires a capability for peeling large volumes of vegetables or fruits. Several types of machines are presently available for this purpose. One of the best types of produce peeler presently available is described in U.S. Pat. No. 3,158,187. The machine described in that patent includes a plurality of segmented rollers in a helically formed configuration with an abrasive on the outer surface of the segments. While this machine has been very satisfactory in most respects, nevertheless, it has several deficiencies. One of these is that the openings be tween each segment on a roller result in loss of available abrading surface within the apparatus. Also, the individual segments tend to cut small notches in the produce being abraded therein.

Another type of machine for this purpose is described in U.S. Pat. No. 3,437,116. The machine described therein includes a feeder element for conveying produce to be peeled through the apparatus while the peeling is done by a plurality of abrasive rollers forming the outer surface of the apparatus.

The two most important variables in peeling produce such as potatoes for a potato chip manufacturing operation include the amount of abrasive surface available, and the effectiveness of the abrasive surface. The amount of surface available depends upon the size and number of abrasive rollers in the apparatus, and on the speed of rotation, while the effectiveness of the abrading surface is largely determined by the load of produce within the apparatus. This load is best controlled by varying the position of a discharge gate.

Additional desirable features of a commercial peeling apparatus include ease of maintenance, minimum operational costs, and optimum quantity of product with minimum waste of the material being peeled. It is desirable from the standpoint of maintenance and op- I crating costs that the abrading members be easily removed and/or replaced without extensive mechanical operations being required.

SUMMARY OF THE INVENTION This invention relates to abrasive peeling machines of the type for peeling fruits and vegetables in commercial food processing operations. Moreparticularly, this invention relates to an abrasive peeling apparatus having a plurality of elongated rotatable rollers mounted in side-by-side relationship which have continuous abrasive surfaces throughout their efi'ective lengths. The rotatable abrading rollers are formed with an outer surface in a helical configuration such that rotation of the rollers results in movement of the produce to be peeled along the axis of the abrading roller and also assists in tumbling the produce within the apparatus.

Abrasive peeling machines of the type of the present invention are used primarily for commercial operations where a continuous peeling capability is desired. For example, in a potato chip manufacturing operation where several tons per hour of potatoes are to be peeled, the apparatus of this invention is especially suitable.

According to this invention, a plurality of abrasive rollers are mounted in an arcuate configuration within the body or housing of the apparatus, and a tumbling action of the produce being peeled is obtained due to rotation of the rollers and by virtue of having oppositely spiraled outer surfaces on different ones of the rollers. The rollers are mounted in the apparatus by means which allow for quick removal and replacement of worn elements or for interchanging the elements to provide a different abrading capability.

It is an object of the present invention to provide a machine which will efficiently remove the skin or peel from fruits and vegetables without damaging the produce being peeled and without abrading away more than the minimum necessary portion of the product being peeled. It is a further object of the invention to provide an improved abrading roller for use in an abrasive peeling apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation of the sealing apparatus of this invention;

FIG. 2 is a top plan view of the apparatus of this in vention;

FIG. 3 is an end elevation, partially broken away, showing the inlet and drive end of the apparatus;

FIG. 4 is an end view of the outlet end of the apparatus;

FIG. 5 is a cross-sectional view taken along the lines 5-5 in FIG. 1;

FIG. 6 is an elevation showing the roller according to the invention;

FIG. 7 is a elevation showing a variation of the roller of the invention;

FIG. 8 is a cross-sectional view taken along the lines 8-8 of FIG. 6;

FIG. 9 is a perspective view of the overall apparatus of this invention including the housings of the apparatus;

FIG. 10 is a perspective view, partially cut away, showing the discharge end mounting means and the abrading rollers of this invention; and

FIG. 1 l is a perspective view of part of the drive train apparatus of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The preferred embodiment of this invention will be described in conjunction with the several figures of the drawings illustrating various aspects of the invention.

In FIG. 1, the abrasive peeling apparatus of this invention is illustrated generally at l, and includes a plurality of abrading rollers 2 carried on shafts 6 and extending throughout most of the length of an abrading chamber within the apparatus 1. The shafts 6 are connected to a drive means through flexible couplings 7, into a casing 5 which encloses timing pulleys and timing drive belts, which in turn are driven by a motor 3 acting through a gear reducer 4. The speed at which the rollers 2 rotate in the apparatus 1 can be controlled by varying the speed of the motor 3, by the use of differing gear ratios in the gear reducer 4, by changing the size of the drive sprockets in the casing 5, or by a combination of these. One preferred drive means includes a constant speed motor and a split pulley variable speed belt drive, sometimes referred to as a variable speed gear motor.

The abrasive peeling apparatus 1 is shown supported by legs 13 and 14, and additionally is supported by frame members 8 throughout the structure as required to give it the necessary rigidity. As best seen in FIGS.

l and 2, a fluid inlet connection 61 is provided which allows for injecting fluid such as water, steam, or other fluid into a fluid line 9 for distribution through spray nozzles 10 located generally throughout the length of the abrading chamber 60 within the peeling apparatus. A feed chute 11 is shown in FIGS. 1 and 2 for feeding the material to be peeled into the inlet end of the peeling apparatus 1. This feed chute can be a shaped inclined piece of sheet metal, for example.

During operation of the abrasive peeler 1, material peeled from the products within the abrading chamber 60 is washed off by the fluid from the spray nozzles 10, and the fluid and peeled material drain through openings between adjacent rollers 2 into a drain pan 12 shown in FIG. 1. This drain pan 12 may open into a sewer or waste collection system, and it may include an auger or other means for conveying the collected peelings out of the drain pan 12 into a waste collection system.

FIG. 3 illustrates the inlet chute 11 and the housing from the inlet end. The drain pan l2 and the legs 13 and additional supporting frame members are also illustrated in this view. Shafts 6 are shown supported by bearings 62 carried by the housing 5. It will be seen that the shafts 6 are mounted in an arcuate pattern such that the rollers carried thereby form a curved lower surface for the abrading chamber 60 as shown in FIGS. 2 and 3.

The discharge end of the apparatus 1 is illustrated in FIG. 4, and also shows the drain pan 12, supporting legs 14 and additional supporting structure. A discharge gate 18 is' shown mounted to the peeler frame by mounting arm 19, and includes an adjusting handle 20 which rotates the discharge gate 18 about a pivot 62 upon movement of the handle 20. The handle 20 includes a means such as a spring loaded pin (not shown) which is received in one of the holes 21 in a curved member 22 mounted near the discharge end of the apparatus. As viewed in FIG. 4, movement of the handle 20 in a counter clockwise direction causes the edge 63 of gate 18 to be rotated downwardly. As will be described below, this controls the height of the material which is being peeled within the abrading chamber 60, thereby controlling the force on the rollers 2.

FIG. 5, which is a view taken through line 55 of FIG. 1 looking toward the discharge end of the peeler, shows the arrangement of the rollers 2 within the peeler 1. The discharge gate 18 including the handle 20 and the mounting arm 19 are also illustrated. FIG. 5 shows an upper wall or baffle 23 mounted on the frame sec tion of the peeler l and located to provide a sidewall for the abrading chamber 60 within the apparatus 1. A lower sidewall 24is shown mounted on the other side of the abrading chamber 60, and the lower surface of the abrading chamber 60 is formed from the rollers 2 mounted in an arcuate pattern below the sidewalls 23 and 24. It can be seen that openings between adjacent rollers are provided to allow the fluid from the nozzles and the peeled material to escape the abrading chamber 60 into the drain pan 12 for subsequent removal from the apparatus. As shown in FIG. 5, the roller 2 which is nearest the upper sidewall 23 is mounted at a higher elevation than any of the other rollers. When viewed as in FIG. 5, each of the rollers are rotated in a clockwise direction, which results in the material to be peeled being forced upward somewhat on the roller surfaces such that it tends to climb toward the sidewall 23 and away from the sidewall 24.

FIG. 9 shows the complete abrasive peeling apparatus 1, including a cover 31 over the variable speed gear motor and drive pulley housing. A hinged sidewall 32 having handles 35 is shown with a double hinge arrangement at 33 and 34 for providing access to the opening within the apparatus 1. The controllable discharge gate 18 is also illustrated including the adjustable handle 20 and the member 22. A discharge spout 36 for conveying the peeled product from the discharge gate 18 to a conveyor or other suitable apparatus is illustrated.

FIG. 11 illustrates a preferred type of drive train for rotating each of the rollers 2 in the same direction. A

plurality of timing pulleys 39 are driven by belts 38 extending between adjacent pulleys. The pulleys are affixed to the shafts 6 (not shown) and as illustrated will each rotate at the same speed due to the fact that the pulleys 39 are each of the same size. It will be apparent that one or more selected shafts could be rotated at different speeds by using different pulley sizes. The timing drive belts 38 are preferably of a flexible non-metallic belting material including teeth formed therein for mating engagement with grooves 66 formed in the sprockets 39. The use of this type of system has resulted in a quiet operation as compared to the use of metallic chains for the drive means, and in addition the belts are longer lived than chains. Driving shaft 37 extends from the gear reducer to provide power to each of the pulleys 39. A flexible coupling between the gear reducer and the housing is preferably included.

A specific preferred embodiment of this invention is illustrated in FIG. 10, which shows an arcuate base member 16 adapted to receive bearings 15 supporting shafts 6. A mating section 17 adapted to fit over the top portion of two of the bearings 15 is detachably secured to the base member 16 to allow easy removal of the discharge end of the roller and bearing supported by base member 16. Upon removal of detachable element 17, the end of the rollers held thereby can be lifted out of the base member 16 and then pulled from the apparatus for repair or replacement as will be described more fully below.

As shown in FIG. 10, the inlet end 67 has an opening for feeding material to be peeled on to the rollers 41 through 47. Each of the rollers is turned in a counterclockwise direction as viewed in FIG. 10, and it will be noted that rollers 41., 42 and 43 are provided with a right hand spiral configuration, while the rollers 45, 46 and 47 are provided with a left hand spiral. As the rollers rotate in a counter-clockwise direction as viewed in FIG. 10, rollers 41, 42 and 43 will tend to urge material back toward the inlet end 67 of the apparatus, while the rollers 45, 46 and 47 will tend to force material toward the discharge end 40 of the apparatus. By arranging the several rollers in an arcuate pattern as illustrated in FIG. 10, the rollers 45, 46 and 47 will have a higher load on them than the rollers 41, 42 and 43. The net result will be that more material will be moved toward the discharge end than will be moved toward the inlet end, even though the same number of rollers are provided for each direction. Actually, the rollers 41, 42 and 43 primarily contribute to a tumbling action within the apparatus, and result in a more uniform peeling of the product going through.

One important aspect of this invention involves a new abrading roller as illustrated in FIG. 6. The roller 2 is shown having a shaft 6 extending therethrough, an outer abrasive surface 25, and a helical configuration, illustrated with a right hand spiral 26, such that rotation of the roller 2 will provide an auger effect tending to drive material contacting the roller 2 along the length thereof. The roller 2 may be formed in a number of different ways. For example, it can be built up from a cylinder by wrapping belting means in a spiral configuration around the cylinder. After the proper outer shape has been attained in this manner, the belting may be covered with a material such as fiberglass impregnated epoxy, and may include a layer of fine screen wire material. A suitable abrasive material, such as silicon carbide or aluminum oxide granules or particles, may then be applied to the outer surface to form a continuous abrading surface 25.

Another manner for forming the roller 2 involves molding a suitable material in the desired helical configuration, preferably with a central opening therethrough. A bonding material can be applied to the outer surface and the abrasive particles distributed thereover to provide a continuous abrading surface.

FIG. 8 illustrates a cross section of a preferred roller 2 shown with a shaft 6 extending through an opening therethrough. As illustrated in FIG. 8, a square outer shaft 30 is attached over the central shaft 6 and preferably welded thereto. The molded body portion 27 of the roller 2 includes an opening therethrough which is formed to fit closely over the outer shaft 30 so that rotation of the shaft will result in rotation of the roller 2. A layer of bonding material 28 is shown coating the molded section 27, and abrasive particles 29 are shown imbedded within the bonding material 28 to provide the abrading surface of the roller. The molded portion 27 can be formed from any suitable material for the ultimate use of the roller. Synthetic and natural rubbers and polymeric materials such as polyvinyl chloride or silicone materials can be used. The materials should be suitable for the acid, steam, or other corrosive environment to which they might be subjected. Generally, molded rubber and plastic materials are preferable.

As seen in FIG. 8, the shaft 6 is eccentric to the cross section of the roller. This will be true no matter at what point along the roller length the cross section is taken. It might also be noted that the shaft 6 is concentric to the circle provided by one complete pitch or revolution of the major radius of the helix. The point of major radius is always displaced 180 from the point of minor radius in any cross section, such that the helical peak and low which travels with rotation of the shaft aids in causing tumbling. There is always a smooth transition from peak to low and back, providing a continuous smooth surface without flat spots or edges so that maximum contact with the curved surfaces of the product being peeled is obtained. Typically, the major radius might be two and one half inches from the shaft center and the minor radius two and one eighth inches from the shaft center, with a helical pitch of about fourteen inches.

A further feature of this aspect of the invention is illustrated in FIG. 7, which shows a roller 2 mounted on a square shaft 30 affixed to a central shaft 6 extending therethrough. The roller 2 is formed from a plurality of segments such as 50 and 51, each of which include one complete revolution of the spiral 26 forming the roller 2. Adjacent segments 50 and 51 are shown abutting each other at 52 to provide a continuous roller surface.

The advantage of forming the roller 2 in segments in this manner is that a worn portion can be removed and replaced without having to dispose of the entire roller. The segments 50 and 51, as well as all segments of the roller, are preferably formed with an opening conforming to the shape of the outer shaft 30. The outer shaft 30 may be any suitable shape, but preferably has a uniform, symmetrical cross-section with angular pr0jections for transmitting torque from the shaft 30 to the molded section 27 of the roller 2. The most convenient shape for this purpose is a square. By forming the segments 50and 51 to include one complete spiral, the sections are interchangeable one with another and can be easily aligned so that the outer surface of the roller 2 is smooth and continuous. Adjacent sections must either be properly aligned, or out of alignment by multiples of 90, which is easily observed by the operator and corrected.

In a typical installation, a roller 2 might be formed of five 14 inch sections, resulting in a roll of inches length andhaving a diameter of about 5 inches. The eccentricity of the roller is such that when 2 rollers are mounted in a non-contacting but close relationship, the maximum gap between two rolls at any point along their length is about 1 inch. This allows the peeled material to drop through the openings, but prevents the products being peeled from being lost into the drain pan 12.

As mentioned above, one of the two primary factors governing the peeling of materials in an apparatus of this type is the abrading surface available per unit time. This is a factor of the length and diameter of the abrading rolls and of their speed of revolution. The other factor governing the amount and quality of peeling is the effectiveness of the abrading surface. This effectiveness is controlled partly by regulating the depth of material within the abrading chamber. As the depth increases,

.the pressure on the abrading surfaces is correspondture. For potato chip manufacture, it is also desirable that the peel and potato removed by the peeling operation should not exceed about 2 percent of the weight of the potato, and at the most not over 5 or 6 percent.

In processing whole potatoes for canning, freezing, production of french fries or the like, it is often desirable to remove percent or more of the peel. In such cases, the loss will be higher and the capacity will be lower. Capacity might be reduced to about 10,000 pounds per hour with losses of about 20 percent when essentially complete peeling is desired (-98 percent peel removal).

As the potatoes are fed into the apparatus, the drive motor 3 operating through gear reducer 4 and suitable belt and pulley connections causes. each of the rollers within the abrading section of the apparatus to rotate in the same direction. Preferably, at least part of the rollers are wound or formed in a manner to drive the potatoes in contact therewith back toward the inlet end of the apparatus. The discharge gate 18 is set to provide the proper pressure of potatoes against the abrading surfaces of the rollers, and to allow the peeled product to discharge at a rate suitable for the feed rate into the machine. Spray nozzles 10 spray a washing fluid, such as water, over the potatoes being peeled to flush the removed peeling away from the potatoes and down through openings between adjacent rollers and into the drain pan 12. The washing fluid also lubricates the material being peeled. The rate of rotation of the abrading rollers may be varied by conventional means, and this control in conjunction with the adjustable discharge gate allows the operator to quickly select conditions to provide satisfactory peeling of the potatoes.

If the abrasive on one of the rollers is worn off, the machine is shut down, the end plate 71 is detached, and the element 17 (FIG. 10) is removed. The roller is lifted out of base 16 and removed from the machine (after separation of the flexible coupling 7 shown in FIG. 1) and either the entire roller or a segment thereof 20 is replaced. The roller is then reinstalled and the machine is ready for operation.

While the invention has been described with reference to specific preferred embodiments thereof, it will be appreciated that numerous variations and modifications could be made without departing from the scope thereof, which is to be defined by the claims.

I claim:

1. An abrasive peeling apparatus comprising:

an abrading chamber;

a plurality of elongated rotatable rollers mounted in a closely spaced non-contacting side-by-side relationship in an arcuate configuration within said chamber forming the lower portion thereof and having continuous abrasive outer surfaces throughout a substantial portion of their length, the surfaces having a helical configuration;

an inlet for loading material into said chamber near one end of said rollers;

means for rotating said rollers; and

an outlet for removal of material from said chamber near the other end of said rollers.

2. The apparatus of claim 1 wherein:

a first part of said rollers are formed with a right hand helical configuration; and

a second part of said rotatable members are formed with a left hand helical configuration.

3. The apparatus of claim 2 wherein all of said rollers are rotatable in the same direction.

4. The apparatus of claim 2 wherein one of the outermost rollers is above the rest of the rollers, and at least the outermost roller on each side is adapted to drive the contents within the chamber toward the inlet end of the chamber, and a plurality of inner rollers are adapted to drive the contents toward the outlet end of the chamber.

5. The apparatus of claim 4 wherein a plurality of fluid dispensing nozzels are disposed along the upper portion of the chamber and an adjustable outlet is provided for regulating the discharge of product from the chamber, the adjustable outlet including a member having a plurality of spaced openings mounted near the outlet end of the chamber and also including an adjusting handle adapted to be set in any one of said openings.

6. The apparatus of claim 4 wherein each of the rollers includes:

a central shaft;

an outer shaft carried by the central shaft and being affixed thereto, said outer shaft having a symmetrical cross-section with angular projections of uniform dimensions throughout its length; and

a body portion fitting over said outer shaft.

7. The apparatus of claim 6 wherein:

said outer shaft has a square cross section;

said body portion fitting over said outer shaft is formed of a plurality of abutting sections each having a length equal to the pitch of the helical surface thereof and having openings therethrough conforming to the shape of the outer shaft.

8. A device for use in an abrasive peeling apparatus comprising:

an elongated roller adapted to be rotated about a central axis;

an abrasive outer surface extending substantially continuously along the effective length of the roller; and

a helical configuration to the outer surface adapted to convey material in contact with the outer surface along the length of the elongated roller upon rotation of the roller.

9. The device of claim 8 wherein the elongated roller has an opening of uniform symmetrical cross-section with angular projections extending therethrough along its longitudinal axis.

10. The device of claim 9 wherein the elongated roller includes a plurality of sections in end-to-end relationship and having mating outer surfaces at the juncture of any two sections.

11. The device of claim 9 wherein the body of the elongated member is a molded material and the outer surface of the elongated roller includes abrading particles embedded in an adhesive.

12. The device of claim 9 wherein the opening contains a central shaft therethrough for rotating the device.

13. The device of claim 12 wherein the central shaft includes an outer shaft of square cross-section carried by the central shaft and the opening of the elongated roller conforms to the shape of said outer shaft.

14. The apparatus of claim 1 wherein each of the rollers has a flexible coupling at one end thereof, and the other end thereof is supported in a hearing which in turn is supported in an arcuate base member having a detachable mating section adapted to fit over the top of the bearing.

i i i i 

1. An abrasive peelIng apparatus comprising: an abrading chamber; a plurality of elongated rotatable rollers mounted in a closely spaced non-contacting side-by-side relationship in an arcuate configuration within said chamber forming the lower portion thereof and having continuous abrasive outer surfaces throughout a substantial portion of their length, the surfaces having a helical configuration; an inlet for loading material into said chamber near one end of said rollers; means for rotating said rollers; and an outlet for removal of material from said chamber near the other end of said rollers.
 2. The apparatus of claim 1 wherein: a first part of said rollers are formed with a right hand helical configuration; and a second part of said rotatable members are formed with a left hand helical configuration.
 3. The apparatus of claim 2 wherein all of said rollers are rotatable in the same direction.
 4. The apparatus of claim 2 wherein one of the outermost rollers is above the rest of the rollers, and at least the outermost roller on each side is adapted to drive the contents within the chamber toward the inlet end of the chamber, and a plurality of inner rollers are adapted to drive the contents toward the outlet end of the chamber.
 5. The apparatus of claim 4 wherein a plurality of fluid dispensing nozzels are disposed along the upper portion of the chamber and an adjustable outlet is provided for regulating the discharge of product from the chamber, the adjustable outlet including a member having a plurality of spaced openings mounted near the outlet end of the chamber and also including an adjusting handle adapted to be set in any one of said openings.
 6. The apparatus of claim 4 wherein each of the rollers includes: a central shaft; an outer shaft carried by the central shaft and being affixed thereto, said outer shaft having a symmetrical cross-section with angular projections of uniform dimensions throughout its length; and a body portion fitting over said outer shaft.
 7. The apparatus of claim 6 wherein: said outer shaft has a square cross section; said body portion fitting over said outer shaft is formed of a plurality of abutting sections each having a length equal to the pitch of the helical surface thereof and having openings therethrough conforming to the shape of the outer shaft.
 8. A device for use in an abrasive peeling apparatus comprising: an elongated roller adapted to be rotated about a central axis; an abrasive outer surface extending substantially continuously along the effective length of the roller; and a helical configuration to the outer surface adapted to convey material in contact with the outer surface along the length of the elongated roller upon rotation of the roller.
 9. The device of claim 8 wherein the elongated roller has an opening of uniform symmetrical cross-section with angular projections extending therethrough along its longitudinal axis.
 10. The device of claim 9 wherein the elongated roller includes a plurality of sections in end-to-end relationship and having mating outer surfaces at the juncture of any two sections.
 11. The device of claim 9 wherein the body of the elongated member is a molded material and the outer surface of the elongated roller includes abrading particles embedded in an adhesive.
 12. The device of claim 9 wherein the opening contains a central shaft therethrough for rotating the device.
 13. The device of claim 12 wherein the central shaft includes an outer shaft of square cross-section carried by the central shaft and the opening of the elongated roller conforms to the shape of said outer shaft.
 14. The apparatus of claim 1 wherein each of the rollers has a flexible coupling at one end thereof, and the other end thereof is supported in a bearing which in turn is supported in an arcuate base member having a detachable mating section adapted to fit over the top of the bearing. 